JP2000141215A - Flattening grinding device and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perfectly execute the flatenning grinding with high accuracy by comprising the coaxially mounted first and second grinding means, a moving means for relatively moving the grinding means in the axial direction and a rotating means for rotating the grinding means around a shaft. SOLUTION: The grinding with a buff 161 is executed as a first stage, and the grinding with a wheel 162 is executed as a second stage. A wafer 101 is sucked in vacuum to a wafer chuck 152, then an X-axis servomotor 155 is driven to rotate an X-shaft ball screw 156, and a bed 151 is moved through a supporting part 154 until the wafer 101 is located on a predetermined grinding start position. Then a rotating mechanism built-in the bed 151 is driven to rotate the wafer 101 through the wafer chuck 152. Simultaneously a spindle motor 171 is driven to rotate the wheel 162 through the spindle 172, and further the buff 161 is rotated through a pin 170.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flattening polishing apparatus and a flattening polishing method for flatly polishing, for example, a plating film or an insulating film formed on the surface of a wafer.

[0002]

2. Description of the Related Art FIG. 10 is a sectional side view showing a manufacturing process of a metal wiring type substrate. A wiring pattern 2 made of copper (Cu) is formed on a surface of a wafer 1 made of silicon, and silicon dioxide (Si) is formed on a surface of the wafer 1 including the wiring pattern 2.
The insulating film 3 made of O ₂ ) is covered (FIG. 2A).

Then, a conductive hole 4 for a laminated wiring pattern is formed in the insulating film 3 by etching (FIG. 1B).
A barrier film 5 made of tantalum (Ta), titanium (Ti), or the like is coated on the surface of the insulating film 3 including the inner surface of the substrate (FIG. 3C), and a seed film 6 made of copper (Cu) is formed by sputtering. (FIG. (D)). Then, a relatively thick copper (Cu) film 7 for a laminated wiring pattern is formed by plating so that the inside of the conduction hole 4 is completely closed (FIG. 10E).
After that, the unnecessary layered wiring pattern film 7 on the barrier film 5
Is removed by polishing to form a laminated wiring pattern 8 to form a final metal wiring type substrate 9 (FIG. 1F).

FIG. 12 is a sectional side view showing a manufacturing process of the element isolation type substrate. Wafer 11 made of, for example, silicon
Device 12 is formed on the surface of
Stopper film 13 made of silicon nitride (SiN) on the surface of
Is coated. Then, a trench hole 14 for element isolation is formed by etching from the stopper film 13 to the wafer 11, and a relatively thick insulating film 15 made of silicon dioxide (SiO ₂ ) is covered so that the inside of the trench hole 14 is completely closed. (Figure (A)). After that, the unnecessary insulating film 15 on the stopper film 13 is polished and removed to form a trench 16, thereby obtaining a final element isolation type substrate 17 (FIG. 1B).

[0005] In the polishing step for manufacturing the above-described substrates 9 and 17, a flattening polishing apparatus is used. FIG.
FIG. 4 is a perspective view schematically showing a conventional flattening and polishing apparatus. The flattening and polishing apparatus 20 includes a rotatable disk-shaped platen 22 having a polishing cloth 21 stuck on the upper surface thereof, and wafers 1 and 11.
Is rotatable, and can be moved up and down (Z direction).
A possible disk-shaped mounting plate 23 and a nozzle 24 for supplying the polishing liquid P onto the polishing pad 21 are provided.

In such a configuration, first, the films 7, 1
With the surfaces of the wafers 1 and 11 on which the 5 is formed face down, the back surface of the wafer 1 is bonded or vacuum-adsorbed to the lower surface of the mount plate 23. Next, the surface plate 22 and the mount plate 23
Is rotated, and the polishing liquid P is supplied from the nozzle 24 onto the polishing pad 21. Then, the mounting plate 23 is lowered, and the surfaces of the wafers 1 and 11 are pressed against the polishing cloth 21.
The films 7 and 15 formed on the surfaces of the wafers 1 and 11 are polished.

[0007]

The above-mentioned substrates 9, 1
In the initial stage of the polishing process when manufacturing the semiconductor device 7, only one type of film, that is, the film 7 for the laminated wiring pattern and the insulating film 15 may be polished. However, in the final stage, since it is necessary to expose the barrier film 5 and the stopper film 13 respectively, not only the laminated wiring pattern film 7 and the insulating film 15 but also the barrier film 5 and the stopper film 13.
Types of films must be polished simultaneously.

When such different types of films, that is, films having different hardnesses, are polished by the conventional flattening polishing device 20, defects such as dishing, erosion (thinning), recess, scratch chemical damage, over polish and under polish are caused. May occur. FIG.
1 is a sectional side view showing a defect in the metal wiring type substrate 9, and FIG. 13 is a sectional side view showing a defect in the element isolation type substrate 16. FIG. 11A and FIG.
This is an example of dishing, and is a defect that the central portions of the multilayer wiring pattern film 7 and the insulating film 15 in a wide portion are excessively polished and dented, and the sectional areas of the multilayer wiring pattern 8 and the trench 16 are insufficient. .

FIGS. 11B and 13B show an example of erosion (thinning). A portion having a high pattern density is excessively polished and dented, and the cross-sectional area of the laminated wiring pattern 8 and the trench 16 is reduced. This is a shortage of defects. FIGS. 11C and 13C show an example of the recess, in which the laminated wiring pattern 8, the insulating film 3, and the trench 1 are formed.
This is a defect that the level of the stacked wiring pattern 8 side and the trench 16 side at the boundary between 6 and the stopper film 13 is lowered, and a step is generated.

FIG. 11D shows an example of scratch chemical damage, which is a defect in which an open / short or a defective resistance value of the laminated wiring pattern 8 occurs.
FIG. 13D shows an example of over-polishing and under-polishing, and a defect that the insulating film 15 remains on the surface due to a shortage of the set removal amount of the insulating film 15 and a set removal of the insulating film 15. Due to overage,
This is a defect that the sectional area of the trench 16 becomes insufficient.

The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide a planarization polishing apparatus and a planarization polishing method capable of performing highly accurate and defect-free planarization polishing.

[0012]

SUMMARY OF THE INVENTION According to the present invention, there is provided a flattening polishing apparatus for polishing a surface of an object to be polished flat, comprising a first polishing means and a second polishing means disposed coaxially. This is achieved by providing a polishing means, a moving means for relatively moving each of the polishing means in the axial direction, and a rotating means for rotating each of the polishing means around the axis.

[0013] Further, according to the present invention, there is provided a flattening / polishing method for polishing a surface of a polished object flat.
The two polishing means arranged concentrically are rotated so that the polishing surface of one of the polishing means protrudes toward the polishing object from the polishing surface of the other polishing means. Is polished, the polishing surface of the other polishing means is protruded from the polishing surface of the one polishing means toward the polishing object side, and the other polishing means is used to polish the surface of the polishing object. You.

According to the above configuration, since the two polishing means are arranged coaxially, there is no need to install a plurality of large stools as in the prior art, and the apparatus can be made compact. Further, since the polished object is subjected to multi-step processing with one chuck, it is possible to suppress variations in processing accuracy due to re-chucking. In addition, since fixed-size high-efficiency processing and constant-pressure high-quality chemical processing are performed in multiple steps, it is possible to process polished objects without defects.

[0015]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are preferred specific examples of the present invention,
Although various technically preferable limits are given, the scope of the present invention is not limited to these modes unless otherwise specified in the following description.

FIG. 1 is a plan view showing the entire configuration of an embodiment of a flattening and polishing apparatus according to the present invention. The flattening and polishing apparatus 100 includes a cassette port 110 into which a wafer 101 to be polished is put, a handling system 120 for positioning the wafer 101 taken out from the cassette port 110, and a wafer 101 positioned by the handling system 120. A polishing head 130 for performing mechanical polishing and a cleaner 140 for cleaning the wafer 101 that has been chemically and mechanically polished by the polishing head 130. Note that the transfer of the wafer 101 between the units is performed by a robot (not shown).

The polishing step in the flattening polishing apparatus 100 having such a configuration will be described. First, a plurality of wafers 101 are stored in parallel in a cassette 102, and the cassette 102 is set in a cassette port 110. Then, one wafer 101 is taken out of the cassette 102 and the handling system 120
Transported to

The conveyed wafer 101 is transferred by the conveyor 121 to the positioning unit 122, where the centering and orientation flat are performed, and the wafer 101 is transferred again to the original position by the conveyor 121. Re-transferred wafer 101
Is transported to the polishing head 130. The transferred wafer 101 is once put into the buffer 131, and then set in the processing unit 132 and subjected to chemical mechanical polishing. The polished wafer 101 is once taken out to the wet station 133 and then transferred to the cleaner 140.

The transported wafer 101 is passed through a cleaning unit 141 for cleaning the chemical, and then transferred to a drying unit 142 for drying the cleaning liquid. Then, the dried wafer 101 is transported again to the handling system 120 and stored in an empty portion of the cassette 102. The cassette 102 that has been subjected to the above steps for all the stored wafers 101 is taken out from the cassette port 110 and transported to the next step.

FIG. 2 is a partial cross-sectional side view showing details of the processing section 132 in the flattening and polishing apparatus 100 of FIG.
The processing section 132 is roughly constituted by a processing table 150 and a processing head 160. The processing table 150
It has a function of mounting and fixing the wafer 101, rotating the wafer 101, and moving the wafer 101 in the X direction. A wafer chuck 152 for vacuum-sucking the wafer 101 is provided on an upper surface of the base 151, and a support 154 having an X-axis ball nut 153 is provided on a lower surface of the base 151.

Then, the X-axis ball nut 153 has
An X-axis ball screw 156 connected to the axis servomotor 155 and extending in the X direction is screwed. In addition, the base 151
A nozzle 157 for supplying a polishing liquid is disposed above the nozzle. Although not shown, the base 151 has a built-in mechanism for rotating the wafer chuck 152.

The processing head 160 moves in the Z direction,
The wafer 101 fixed to the processing table 150 is
It has the function of performing chemical mechanical polishing at the stage. Wafer 101
A disk-shaped buff (first polishing means) 161 having substantially the same diameter as
An annular wheel (second polishing means) 162 having an inner diameter larger than the diameter of the buff 161 is disposed coaxially, that is, concentrically. The buff 161 is adhesively fixed to the lower surface of an annular metal platen (first polishing means) 163, and the wheel 162 is adhesively fixed to the lower surface of an annular metal tool flange (second polishing means) 164. Have been.

One end of a shaft (fixed shaft) 165 is fixed to a central hole of the metal surface plate 163 via a flange 167 having a bearing 166. This flange 167
Has an outer peripheral surface formed in a tapered shape, and is fitted and fixed to an inner peripheral surface of a hole at the center of a metal platen 163 formed in a similar tapered shape. On the upper surface side of the metal tool flange 164, counterbores 168 are provided at equal angular intervals.

Inside the counterbore 168, a spring 169 is provided.
Is inserted so as to penetrate to the lower surface side of the metal tool flange 164. The tip of the pin 170 is screwed to the upper surface of the metal platen 163. A main spindle (rotating means) 172 having a main spindle motor (rotating means) 171 is fixed to the upper surface of the metal tool flange 164, and an air cylinder (moving means) 173 is fixed to the upper part of the main spindle motor 171. ing.

The shaft 165 is disposed so as to penetrate through a central hole of the metal tool flange 164 through central portions of the spindle spindle 172, the spindle motor 171 and the air cylinder 173. The other end of the shaft 165 is provided with the piston 1 of the air cylinder 173.
73a is fixed. And the shaft 165 is
It is formed in a hollow cylindrical shape for supplying a polishing liquid.

A support 175 having a Z-axis ball nut 174 is provided on the outer peripheral surface of the spindle motor 171. And the support part 175 is the Z-axis guide 1
76, and the Z-axis ball nut 174 has
Z connected to the Z-axis servomotor 177 and extending in the Z direction
The shaft ball screw 178 is screwed.

FIGS. 3A and 3B are a plan view and a sectional side view showing a detailed example of the metal surface plate 163 of FIG. A cross-shaped groove 163a is formed on the lower surface of the metal platen 163, that is, the surface to which the buff 161 is bonded and fixed. A groove 163a is provided at the tip of the cross of the groove 163a.
Through hole 16 that penetrates from the bottom of metal plate to the peripheral surface of metal platen 163
3b is provided.

FIGS. 4A and 4B show the buff 161 of FIG.
It is a top view which shows the example of a detail. Buff 1 shown in FIG.
61A is provided with a plurality of cross-shaped holes 161Aa following the groove 163a of the metal surface plate 163. Also,
The buff 161B shown in FIG. 4B is further provided with a plurality of holes 161Ba radially. The buff 161A or 161B is bonded and fixed to the lower surface of the metal platen 163 having the above configuration, that is, the surface on which the groove 163a is formed.

Thus, the polishing liquid supplied from the hollow portion of the shaft 165 is supplied to the central hole 163 of the metal platen 163.
c and flows into the groove 163a. While the polishing liquid is flowing in the groove 163a, a part of the polishing liquid is buffed.
1A or 161B passes through the hole 161Aa or 161Ba to the polishing surface of the buff 161A or 161B, and the remaining, that is, excess polishing liquid is discharged from the outer peripheral surface of the buff 161A or 161B through the through hole 163b of the metal platen 163. Is done. Therefore, the polishing liquid spreads over the entire polishing surface of the buff 161A or 161B, so that polishing accuracy and polishing efficiency can be improved.

FIG. 5 is a sectional side view showing another example of the flange connecting the metal surface plate and the shaft. The flange 167 'has an outer peripheral surface formed in a hemispherical shape, and is slidably adhered to an inner peripheral surface of a central hole of a metal platen 163' formed in a similar hemispherical shape. I have.

According to such a configuration, for example, the wafer 1
01 even if its surface is inclined,
When the polished surface of the buff 161 comes into contact with the surface of the buff 161, the metal platen 163 ′ swings about the flange 167 ′, so that the polished surface of the buff 161 can always contact the surface of the wafer 101 horizontally. Becomes Therefore, the wafer 10
1 can make the flatness of the surface highly accurate.

An operation example of the above configuration will be described with reference to FIGS. Here, buff 161
For example, a soft buff is used, and as a polishing liquid, a chemical solution of an etchant such as nitric acid (HNO ₃ ) is used. Further, as the wheel 162, for example, a hard wheel on which hard alumina abrasive grains are fixed, and as the polishing liquid, for example, a slurry in which alumina abrasive grains are dispersed with a weak acid is used. As a first step, polishing using a buff 161 is performed (see FIG. 6), and as a second step, polishing using a wheel 162 is performed (see FIG. 7).

First, the wafer 10 is placed on the wafer chuck 152.
When the wafer 1 is vacuum-sucked, the X-axis servo motor 155 is driven to rotate the X-axis ball screw 156, and the base 151 is moved via the support 154 until the wafer 101 reaches a predetermined polishing start position. Then, the rotation mechanism built in the base 151 is driven to rotate the wafer 101 via the wafer chuck 152. At the same time, the main spindle motor 171 is driven to rotate the wheel 162 via the main spindle 172, and the buff 161 is further rotated via the pin 170.

Next, the Z-axis servomotor 177 is driven to rotate the Z-axis ball screw 178 so that the polished surface of the wheel 162 is separated from the surface of the wafer 101 which is vacuum-adsorbed to the wafer chuck 152 by a predetermined distance. The support 175 is lowered along the Z-axis guide 176 until the state is reached. Then, a chemical 1 is supplied from a supply device (not shown)
It is supplied to the buff 161 through the hollow portion 65 and the groove 163 a of the metal platen 163. At the same time, the air cylinder 173
Pressurized supply port 17 provided in cylinder 173b
Air is supplied to 3c to lower the metal platen 163 via the piston 173a and the shaft 165.

At this time, the metal platen 163 is
9 is compressed, and the polished surface of the buff 161 protrudes from the polished surface of the wheel 162. And buff 161
Is pressed against the surface of the wafer 101, the X-axis servomotor 155 is driven to rotate the X-axis ball screw 156, and the base 151 is reciprocated via the support 154,
The wafer 101 is chemically and mechanically polished. The absolute value of the polishing amount at this time can be controlled mainly by the pressure of the air cylinder 173 and the speed at which the buff 161 passes through the wafer 101. After the polishing, the supply of the chemical is stopped, pure water is supplied to the surface of the wafer 101 through a nozzle (not shown), and the chemical remaining on the surface of the wafer 101 is washed and removed.

As described above, in the first polishing step, the selectivity, that is, for example, when the wafer 101 is formed of a metal wiring type substrate, because of the use of a soft buff and the etching using an acid. In the case, the ratio of the polishing rate between the laminated wiring pattern film 7 and the barrier film 5 becomes large, and in the case of the element isolation type substrate, the ratio of the polishing rate between the insulating film 15 and the stopper film 13 becomes large. Stopping accuracy increases.

Accordingly, although dishing and erosion increase and the polishing removal rate decreases, the absolute value of dishing and erosion is reduced by setting the absolute value of the total polishing removal amount in the first stage to be small, and the polishing processing time is reduced. Can be shortened. In addition, since the buff 161 is a processing that has a strong chemical reaction, the surface of the wafer 101 is less damaged and can be made a mechanically smooth surface.

Subsequently, the cylinder 1 of the air cylinder 173
Air is supplied to the retreat-side supply port 173d provided in the 73b, the metal platen 163 is raised via the piston 173a and the shaft 165, and the polished surface of the buff 161 is separated from the surface of the wafer 101. At this time, metal surface plate 1
The upper surface of the baffle 63 is pressed against the lower surface of the metal tool flange 164 by the restoring force of the spring 169.
The polished surface of No. 1 is retracted from the polished surface of the wheel 162.

Then, the slurry is supplied from a supply device (not shown) to the surface of the wafer 101 via the nozzle 157.
At the same time, the Z-axis servo motor 177 is driven in the opposite direction to rotate the Z-axis ball screw
5 is lowered along the Z-axis guide 176. Then, the polished surface of the wheel 162 is pressed against the surface of the wafer 101, the X-axis servo motor 155 is driven to rotate the X-axis ball screw 156, and the base 151 is reciprocated via the support 154, and the wafer 101 is chemically treated. Mechanical polishing.
Note that the absolute value of the polishing amount at this time is mainly determined by the pressing amount by the Z-axis servomotor 177 and the wafer 1 of the wheel 162.
01 can be controlled by the passing speed. After the polishing, the supply of the slurry is stopped, pure water and a chemical solution are supplied to the surface of the wafer 101 through a nozzle (not shown), and the slurry and particles remaining on the surface of the wafer 101 are washed and removed.

As described above, in the second polishing step, for example, the wafer 101 is formed of a metal wiring type due to the use of a hard wheel and the low selection ratio of the slurry due to the weak acid. In the case of a substrate, a portion of the laminated wiring pattern film 7 and a portion where the barrier film 5 is exposed,
In the case of an element separation type substrate, polishing of the portion of the insulating film 15 and the portion where the stopper film 13 is exposed proceeds uniformly. Therefore, compared with the case where a conventional pad and slurry are used, dishing and erosion are small, and high-efficiency polishing with a relatively high polishing removal rate can be performed.

In the above-described embodiment of the flattening polishing method, the rough polishing by the buff 161 is performed in the first stage, and the final polishing by the wheel 162 is performed in the second stage. May be performed, and finish polishing by the buff 161 may be performed in the second stage. In this case, the polishing by the wheel 162 has a small selectivity, so that the dimensional stop accuracy is not sufficient, and furthermore, since the polishing is a high-efficiency polishing by a hard wheel, micro-roughness and damage remain on the surface of the wafer 101. About area, for example, wafer 10
When 1 is a metal wiring type substrate, a state in which a layered wiring pattern film 7 slightly remains on the barrier film 5, and when an element separation type substrate, an insulating film 15 slightly on the stopper film 13. Ends with

Then, the dimensional accuracy is increased by polishing with the buff 161 and the remaining damaged layer is removed. Further, the polishing by the buff 161 and the polishing by the wheel 162 may be performed simultaneously. According to this method, rough and finish polishing can be performed at one time, and the number of polishing steps can be greatly reduced.

FIGS. 8 and 9 show the dishing evaluation and the erosion evaluation by observing the surface profiles when the polishing of this embodiment and the conventional polishing are performed. Conventional polishing conditions are as follows: a pad (foamed polyurethane pad IC-1000 manufactured by Rodale Inc. (USA)) is set at 30 rpm to 60 rpm.
m and rotate at 150 kgf / cm ² -250
The conditions were such that a slurry (alumina slurry C4010 manufactured by Cabot Corporation (US)) was supplied under pressure at a pressure of kgf / cm ² .

FIG. 8A shows a dishing state of a wiring pattern having a width of 500 μm by polishing according to the present embodiment, and the dishing amount is about 300 °. FIG.
FIG. 8B shows the relationship between the wiring width and the dishing amount. The white circles are data obtained by conventional polishing, and the black circles are those in FIG.
This is the data of FIG. As is clear from these figures, according to the polishing of the present embodiment, dishing can be greatly improved as compared with the conventional polishing.

FIG. 9A shows an erosion state of a portion having a wiring density of 50% and a line and space of 100 μm by polishing in this embodiment, and the maximum erosion amount is about 80 °. FIG. 9B shows the area-dependent relationship of the erosion. There is no data corresponding to FIG. 11A, but the erosion amount is 75 n at 2.00 μm.
m (750 °), 0.25 μm, erosion amount is 30
As is clear from comparison with nm (300 °), the polishing according to the present embodiment can significantly improve the erosion as compared with the conventional polishing.

[0046]

As described above, according to the present invention,
High-precision, defect-free planarization polishing can be performed.

[Brief description of the drawings]

FIG. 1 is a plan view showing an overall configuration of an embodiment of a flattening and polishing apparatus of the present invention.

FIG. 2 is a partial cross-sectional side view showing details of a processed part in the flattening and polishing apparatus of FIG. 1;

FIG. 3 is a plan view and a cross-sectional side view showing a detailed example of the metal surface plate of FIG. 2;

FIG. 4 is a plan view showing a detailed example of the buff of FIG. 2;

5 is a cross-sectional side view showing another example of a flange connecting a metal surface plate and a shaft in the flattening and polishing apparatus of FIG. 1;

FIG. 6 is a first sectional side view showing an operation example of the flattening and polishing apparatus of FIG. 1;

FIG. 7 is a second cross-sectional side view illustrating an operation example of the planarization polishing apparatus of FIG. 1;

FIG. 8 is a view showing dishing evaluation by the flattening polishing apparatus of FIG. 1 and a conventional polishing apparatus.

9 is a view showing erosion evaluation by the flattening polishing apparatus of FIG. 1 and a conventional polishing apparatus.

FIG. 10 is a sectional side view showing a manufacturing process of the metal wiring type substrate.

FIG. 11 is a sectional side view showing a defect in the metal wiring type substrate.

FIG. 12 is a sectional side view showing a manufacturing process of the element separation type substrate.

FIG. 13 is a sectional side view showing a defect in the element isolation type substrate.

FIG. 14 is a perspective view schematically showing a conventional flattening and polishing apparatus.

[Explanation of symbols]

100: Flattening polishing device, 101: Wafer, 1
10: cassette port, 120: handling system, 130: polishing head, 132
..Processing part, 140 cleaner, 150 processing table, 151 base, 152 wafer chuck, 153 X-axis ball nut, 154 support part, 155 ..X-axis servo motor, 156... X
Shaft ball screw, 157 nozzle, 160 processing head, 161 buff, 162 wheel, 1
63: metal surface plate, 164: metal tool flange, 165: shaft, 166: bearing, 16
7 ... Flange, 168 ... Counterbore, 169 ...
Spring, 170 Pin, 171 Spindle spindle motor, 172 Spindle spindle, 173 Air cylinder, 174 Z-ball nut, 175
..Support portions, 176... Z-axis guides, 177.
Axis servo motor, 178 ... Z axis ball screw

Claims (11)

[Claims] 1. A flattening polishing apparatus for polishing a surface of an object to be polished flat, wherein a first polishing means and a second polishing means disposed coaxially, and each of the polishing means are relatively moved in an axial direction. A flattening polishing apparatus comprising: moving means; and rotating means for rotating each of the polishing means around an axis. 2. The flattening and polishing apparatus according to claim 1, wherein the shaft is formed in a hollow cylindrical shape for supplying a polishing liquid. 3. The flattening polishing apparatus according to claim 1, wherein each of the polishing means is arranged concentrically. 4. A flattening polishing apparatus for polishing a surface of an object to be polished flat, comprising: a fixed shaft formed in a hollow cylindrical shape for supplying a polishing liquid; and one end of the fixed shaft. A disk-shaped first polishing means rotatable around an axis, and an annular second polishing means locked on the first polishing means and arranged on the outer periphery thereof and rotatable about the axis. A moving means disposed at the other end of the fixed shaft, for moving the first polishing means in the axial direction together with the fixed shaft to change a relative position of a polishing surface of each polishing means, And a rotating means for rotating each of the polishing means around an axis. 5. The flattening polishing apparatus according to claim 4, wherein the first polishing means is provided at one end of the fixed shaft via a flange having a bearing. 6. A flattening polishing apparatus according to claim 5, wherein a contact surface between said flange and said first polishing means is formed in a tapered shape. 7. The flattening polishing apparatus according to claim 5, wherein a contact surface between said flange and said first polishing means is formed in a spherical shape. 8. A flattening polishing method for polishing a surface of an object to be polished flat, wherein two concentrically arranged polishing means are rotated, and a polishing surface of one of the polishing means is rotated by the other of the polishing means. A surface of the polished object is polished by one of the polishing means, and a polished surface of the other polishing means is protruded from the polished surface of the one polishing means to the polished object side. And polishing the surface of the polished object with the other polishing means. 9. The flattening polishing method according to claim 8, wherein a polishing liquid is injected into a hollow portion of a central shaft and supplied to a polishing surface when polishing is performed by the polishing means provided inside. 10. A flattening polishing method for polishing a surface of a polishing object flat, wherein two concentrically arranged polishing means are rotated, and each of the polishing means simultaneously polishes the surface of the polishing object. A flattening polishing method characterized by the above-mentioned. 11. The flattening polishing method according to claim 10, wherein a polishing liquid is injected into a hollow portion of a central shaft and supplied to a polishing surface when polishing by each of the polishing means.